It is previously known electromechanical lock systems wherein keys are assigned to different users in a conventional way similar to the way keys are distributed in a mechanical lock system. However, this distribution is difficult to accomplish and it is a cumbersome procedure to distribute new keys. Also, there is always a danger that an unauthorised person obtains a system key, leading to security risks etc.
Another problem is that electronic codes can be copied, e.g. by “recording” the code by means of a reader, whereby copies can be present in the key system without the knowledge of the system owner.
Yet another problem of prior art is that key blanks can be used by anyone, posing a security risk.
The U.S. patent document U.S. Pat. No. 6,005,487 (Hyatt, Jr. et al) discloses an electronic security system including an electronic lock mechanism and an electronic key. To eliminate the requirement of costly rekeying in the event of a key loss or to eliminate the possibility of internal fraud and theft, the system according to Hyatt, Jr et al provides for a change of an ID code of a key or a lock. However, the above mentioned problems of prior art are not addressed by this system.